Due to the huge volume of human sanitary wastewater in the world today, it has made wastewater treatment very important; Because its discharge can cause irreparable damage to the environment, and on the other hand, if human sanitary wastewater treatment is carried out, it can contribute greatly to the water shortage crisis and agricultural and economic prosperity in every Please be a country. Human sanitary sewage is produced by humans as a result of daily water consumption to perform daily sanitary tasks such as bathing, washing clothes, washing dishes and cleaning, etc.
Human sanitary wastewater treatment methods
Three general methods can be used for wastewater treatment. These three methods are:
Physical method
This method is one of the first methods in the treatment of sanitary waste water, and due to the simplicity of the process, it is used in the separation of materials. The physical method is less expensive than other methods, that’s why this purification method is used most of the time. This method includes: garbage removal, granulation, sedimentation, filtration, degreasing and flotation.
Chemical method
This method is more complicated than the physical method. In the chemical method, the process of separation or conversion of materials takes place using substances and chemical reactions. The complexity of this method has made it more difficult to use the chemical method and as a result less of this process is used in the purification system. Another problem of this method is the high cost of purchasing and maintaining chemicals, which prevents the use of this method in the purification system. This method includes: ozonation, chlorination, pH adjustment, coagulation and flocculation, and disinfection with chlorine.
Biological method
In this method, micro-organisms, especially bacteria, are used in the treatment of human sanitary wastewater; Because the organic materials in it absorb the waste water and use it for cell proliferation and energy. As you know, organic materials make up the majority of pollutants and make the use of biological methods common. This method with a very low cost can purify a major share of pollutants, which includes: aerobic and anaerobic.
Considering that it is not possible to purify wastewater using one of the mentioned methods alone, a combination of all the above methods is used in the purification of human wastewater.
Human wastewater treatment system processes
As we said, the biological method by combining two other methods is one of the common methods in purification, which takes place in the initial stages of purification, disinfection and pre-purification; That is why the biological method is mostly used. Garbage of coarse particles in sewage is usually done by the garbage collection unit. This is done to prevent clogging of pipes.
Garbage collectors are made in different sizes and capacities according to the droplets of passing particles, wastewater flow rate, wastewater pH, whether it is manual or mechanical, and site conditions. EAAS select activated sludge system that has extensive aeration as one of the best methods for system aeration. Sludge disposal is one of the problems of wastewater treatment plants, and this has caused the activated sludge system to be paid more attention; Because it produces less sludge than other systems.
Disinfection must be done after using this system. The disinfection process is done to prevent germs and diseases from entering water sources.
Sanitary wastewater quality:
Due to the origin of wastewater production (human activity), it has almost the same quality all over the world, human sanitary wastewater is the result of the combination of black water (toilet) and gray water (bathing, washing dishes, washing clothes, etc.) in the country. The developed facilities of these two parts are separated from each other so that the purification steps can be done more easily; But in Iran, both of them enter a common sewage network and must be treated as sewage under the human sewage treatment system.
The quality of wastewater depends on factors such as the level of health, culture, welfare and many other factors that make them slightly different from each other; But all of them are within a limited range of pollutants and can be referred to for the construction of a wastewater treatment unit.
The qualitative analysis of human wastewater in Iran, if no test is performed on it, is considered for the design of a sanitary wastewater treatment system unit according to the table below.
Sanitary wastewater production per capita:
To build a treatment unit, we need wastewater production per capita. The volume of wastewater produced per person during the day is called per capita wastewater production. The production per capita is not the same everywhere and depends on many factors such as the level of health, culture, weather conditions, consumption pattern, land use, etc. The amount of wastewater produced by a complex can also be estimated from the water consumption bill. If the bill is not available, this per capita can be estimated in different uses in Iran according to the table below.
Characteristics of human sewage treatment system
Today, human sewage treatment systems are used in all developed and developing countries and even in war-torn countries such as Afghanistan and Iraq. These countries are customers of these production systems of Iranian companies. The advantages of human sanitary sewage treatment devices are:
Proper efficiency and obtaining the standard approval of the Environmental Protection Organization
Performance without creating odors and environmental pollution
Quick and easy construction
The ability to change the location of the human sewage treatment device even after installation
The possibility of upgrading the capacity of the treatment system during operation
Use of effluent for agriculture and green space irrigation
Human wastewater treatment processes
These processes have many variations and scope, and choosing the right process among them is important.
Extended Aerated Activated Sludge (EAAS) method:
This process is the upgraded process of activated sludge, which has eliminated the disadvantages of the activated sludge system by making a series of changes in it. This process is used to purify the sanitary wastewater of small communities such as residential settlements, workshops, factories, hotels and hospitals, etc. The resistance of this system to hydraulic shocks and the quality of wastewater is very high, and currently, this process is used for wastewater treatment in most wastewater treatment plants.
MBBR method:
In places where space is limited, MBBR wastewater treatment can be used to treat human sanitary wastewater. This method is the activated sludge process with extensive aeration, which is used to reduce the volume of the aeration tank and thus reduce the space occupied by the floating media packing in the aeration tank, and also reduces the initial investment cost.
Among the other advantages of this system, it should be mentioned the high shock resistance as well as increasing the capacity of the wastewater treatment plant during the operation period by adding and reducing the amount of packing media in the aeration pond.
IFAS method:
Wastewater treatment with the IFAS process is similar to the MBBR process, which is based on the activated sludge method with extensive aeration; with the difference that in this process, fixed media packing is used instead of floating media packing, and it causes the growth of aerobic microorganisms on these media, and with the increase in the population of microorganisms per unit volume and the decrease in the ratio of F to M in the aeration pond, it causes Increasing the efficiency of the treatment system and reducing the volume of the sanitary sewage treatment device. Among the advantages of this method, we can mention high shock resistance, proper purification efficiency, reducing the volume of the tank, as well as reducing the initial investment, etc.
A2O method:
This process is the activated sludge process with extensive aeration, which is done for the additional treatment of sanitary wastewater and removing the parameters for surface water and absorbent wells, which are the most important places of wastewater discharge. In order to remove nitrate and phosphate from the wastewater outlet, an anaerobic unit and an anoxic unit have been added to it. From this process, in order to treat human wastewater in places where, in addition to reducing BOD, COD, etc., removal of nitrate and phosphate is also on the agenda. They use this method to discharge treated wastewater to surface water and absorbent wells, where nitrate and phosphate removal is also required.
Places that use the human sewage treatment system:
It can almost be said that there is sewage in all the existing places where people live and work, and wherever there is sewage, a human sewage treatment system is needed. Places such as hotels, restaurants, factories, hospitals, labor camps, refineries, petrochemicals, universities, dormitories, recreational complexes and parks, etc. Sewage house so as not to harm the environment and use the treated sewage for their own use.
Sanitary human sewage treatment units:
Garbage basket, balancing unit (septic tank), aeration lagoon, sedimentation tank, anti-foam unit, chlorine injection unit, pumping station to filters, sand and carbon filtration (multimedia), sanitary wastewater treatment plant outlet storage unit Requirement, sludge storage tank, equipment room and electrical panel, airlift pump.
The quality of the effluent from the human sanitary sewage treatment device:
The Environmental Protection Organization has published a standard for sanitary wastewater treatment that the treatment systems should be able to reduce the pollutant parameters in the wastewater to this extent. These three standards are:
Agriculture and green space irrigation:
BOD5<100 mg/l COD<200 mg/l TSS<100 mg/l
Discharge to surface water:
mg/l (moment 50) COD<60 mg/l (moment 100) TSS<40 mg/l (moment 60)
Discharge to the absorbent well:
mg/l (moment 100) COD<60 mg/l (moment 50)
Three parameters are required for the design of sanitary sewage treatment plant:
The quality of wastewater entering the treatment plant: according to the analysis of the incoming wastewater and if the table of wastewater parameters (given above) is not available.
Inlet flow to the treatment plant: according to the per capita production of wastewater (explained above)
The quality of the effluent from the treatment plant: according to the place where the output of the treatment plant is going to be used (the places used are listed above)
The price of the sanitary human sewage treatment device
The amount that should be considered for investing in the treatment of human sanitary wastewater is very affordable and the investment will be returned to the investor in a short period of time; Because both of them cause no environmental pollution and sustainable development in the long term, and with the use of purified wastewater in agriculture and green space irrigation, it can be said that the capital will soon return to the investor. With this explanation, the necessary cost for wastewater treatment depends on factors such as the structure of the treatment plant, the treatment process and the place where the treatment plant is to be built. The best option for sanitary wastewater is metal devices that are portable and are made in the factory of Ati Sazan Arsham Sanat and transported to the project site for installation and operation.
Material of the treatment plant structure:
The sewage treatment plant structure can be made of metal, concrete, polyethylene and fiberglass. Due to the difference in the price of the materials used in the structure of each treatment plant, the price of each of them will also be different.
Purification process:
The process used in wastewater treatment also affects the price of the treatment plant because it determines the equipment used in the treatment plant and the different units of the sewage treatment device and the dimensions of the different parts of the treatment plant.
Volume of wastewater produced daily:
The amount of wastewater produced in the area covered by the wastewater treatment system is also important in the price of the treatment plant because it determines the size of the treatment plant and the capacity of the equipment used in the treatment plant.
Our company has designed, built, implemented, launched and operated wastewater treatment systems by taking advantage of world-class knowledge as well as the experience of doing hundreds of projects in the field of human wastewater treatment, as well as using new technologies. Now introduce itself as one of the top companies in the water and sewage industry and the environment.
Human wastewater treatment process in the treatment plant
First, human sewage enters the sewage collection network through the pipelines in the buildings, and at the entrance of the sewage septic tank, it is first passed through a garbage collection basket, and in a granulation channel, the sand grains in the sewage are removed. and it is directed into the sanitary wastewater treatment device by the sludge pumps in the pumping station, so that in the aerobic biological tank, under the influence of the activity of aerobic microorganisms, it causes the removal of pollutants in the wastewater and the reduction of BOD and COD.
Then the sewage enters the sedimentation area and the sludge formed in the aeration tank is settled in the sedimentation basin under the influence of gravity and the excess sludge is transferred to the sludge storage tank by the airlift pump and kept there until the time of discharge. . The clear output from the sedimentation congressional overflows enters the chlorination section and after disinfection and disinfection, they leave the human sanitary wastewater treatment system.
